Electronic control systems are used in order to operate drive units for vehicles. With the aid of the electronic control systems, the parameter(s), which are adjustable at the drive unit, are fixed in dependence upon input quantities. Some of these electronic control systems operate on the basis of a torque structure, that is, torque values are inputted as desired values for the control system by the driver and, if required, by additional systems including: road speed controller, electronic stability programs, transmission controls, et cetera. These torque values are converted by the control system while considering additional quantities into adjusting variables for the power parameter(s) of the drive motor. An example of such a torque structure is known, for example, from DE 42 39 711 A1 (U.S. Pat. No. 5,558,178).
In such control systems, care must be taken that also a negative acceleration torque (engine braking) can be realized. In conventional control systems, this takes place by interrupting the fuel injection under specific conditions. For example, the interruption of the fuel supply is triggered in spark-ignition engines when the accelerator pedal is not depressed and the engine rpm lies above an rpm limit (see, for example, DE 44 45 462 A1). In controls for diesel engines, the fuel injection quantity is reduced to zero when the accelerator pedal is continuously released or withdrawn. In the course of unifying the control systems, there is therefore the need for a procedure for realizing a negative acceleration torque with the objective of vehicle deceleration. The same (identical) torque structure is used independently of the type of drive (for example, spark-ignition engine or diesel engine or electric motor).